Vascular Plants of the Gila Wilderness

Presented in Association with the
Western New Mexico University Department of Natural Sciences

Key to the genus Cheilanthes in the Gila National Forest

The genus Cheilanthes represents the largest number of ferns of any genus of ferns in the Gila National Forest. Like most other ferns in this area, they are highly arid adapted. Their ability to withstand long periods of drought is attributable to the presence of hairs, scales and other adaptations including the tolerance of very low water content in their tissues. Since water is necessary for sexual reproduction in ferns, the Cheilanthes ferns may reproduce to a large extent through other means.
When keying out Cheilanthes ferns, it is very important to use magnification to view the scales or cilia. There are some species that are so similar that some individuals are difficult to assign with certainly to one species or the other. This key closely follows the strategy developed in Flora of North America.

1. Scales evident on abaxial surface of costae, with or without hairs.....2.
2. Costal scale margins usually entire, sometimes denticulate but with no more than one or two small hairs.....3.
3. Costal scales linear and inconspicuous, no wider than 0.4mm .....Cheilanthes tomentosa.
3. Costal scales lanceolate and more than 0.4mm wide.....4.
4. Both adaxial and abaxial surfaces are devoid of cilia (if cilia are visible on abaxial surface, consider C. wootonii), plants are usually found on north facing exposure.....Cheilanthes fendleri.
4. Cilia present on both adaxial and abaxial surfaces of terminal segments, plants commonly on south or east facing exposure (but if scales cover the abaxial surface of the terminal segments, look for cilia on the proximal part of the scales and consider C. lindheimeri) .....Cheilanthes eatonii.
2. Costal scale margins with cilia over at least 1/2 their length .....5.
5. Adaxial surface densely tomentose, ciliate scales obscure the abaxial terminal segments (otherwise, consider C. eatonii).....Cheilanthes lindheimeri.
5. Adaxial surface glabrous or sparsely pubescent.....6.
6. Pinnae glabrous adaxially, stem scales not bicolored; distal portion of costal scales frequently without cilia.....Cheilanthes wootonii.
6. Pinnae with sparse adaxial pubescence, costal scales usually ciliate for their entire length, stem scales bicolored and persistant.....Cheilanthes yavapensis.
1. Scales absent from abaxial surface of costae, with or without hairs.....7.
7. Most fronds over 20cm tall, obviously pinnate-pinnatifid pinnae articulate to rachis through a swollen node.....Cheilanthes bonariensis.
7. Most fronds less than 20cm tall and commonly more than twice pinnate toward the base, pinnae do not articulate to rachis through a swollen node.....8.
8. Most plants growing tightly clustered on nearly vertical cliff faces, rachis not grooved, abaxial surface of terminal segments densely hairly.....Cheilanthes feei.
8. Most plants spreading in cracks in bedrock on sloping but not vertical terrain, rachis grooved, abaxial surface of terminal segments nearly glabrous.....Cheilanthes wrightii.

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